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Abstract Detail


Evolutionary Developmental Biology (Evo-Devo)

Almeida, Ana Maria R [1], Bartlett, Madelaine [1], Specht, Chelsea [2].

Class B gene expression in the Zingiberales and its role in the evolution of pollination syndromes through alterations in floral form.

Numerous elegant genetic experiments in Arabidopsis have established the classical ABC model of floral development in which MADS-box containing genes are responsible for defining floral organ identity. In Arabidopsis, B class genes (APETALA 3 (AP3) and PISTALLATA (PI)) together with the C class gene AGAMOUS (AG) are involved in stamen specification. In the order Zingiberales floral diversity is mainly due to changes in the stamen whorl. Those changes are related to specialized pollination syndromes with birds, bees, bats, moths, butterflies and primates. Zingiberales contains approximately 25,000 species roughly divided into two groups: the banana families (Musaceae, Strelitziaceae, Lowiaceae and Heliconiaceae) and the ginger families (Costaceae, Zingiberaceae, Cannaceae and Marantaceae). In the first group, fertile stamen numbers vary from 5 to 6, with reduction to 5 fertile stamens achieved via stamen abortion or the formation of a single staminode (an infertile stamen). In the ginger families, however, the number of fertile stamens is greatly reduced (one or one half). The remaining primordia develop into petaloid staminodes. Also, within Costaceae and Zingiberaceae, a new structure is formed, the labellum, as a result of the fusion of the staminodes. The staminodes, as well as the labellum, form the bulk of the floral display in the ginger families. Here we present data on the role of B class genes (AP3 and PI) in stamen development and the evolution of floral morphology within this group. B class gene homologs from taxa spanning the order were characterized and a phylogenetic reconstruction of their evolutionary history is presented. B class gene expression patterns during floral development from taxa with different floral morphologies were also studied via in situ hybridization.


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1 - University of California, Berkeley, Plant and Microbial Biology, 111 Koshland Hall, Berkeley, CA, 94720-3102, United States
2 - University of California, Berkeley, Plant and Microbial Biology, 111 Koshland Hall MC 3102, Berkeley, California, 94720-3102, USA

Keywords:
floral morphology
Zingiberales
gene family evolution
adaptive evolution
ABC model.

Presentation Type: Oral Paper:Papers for Topics
Session: 62
Location: Cottonwood A/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 10:15 AM
Number: 62001
Abstract ID:234


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